GB1596217A

GB1596217A - High-intensity discharge lamps

Info

Publication number: GB1596217A
Application number: GB9749/78A
Authority: GB
Original assignee: Westinghouse Electric Corp
Current assignee: CBS Corp
Priority date: 1977-03-15
Filing date: 1978-03-13
Publication date: 1981-08-19
Also published as: JPS5758024B2; BE864889A; JPS53115582A; US4186327A; DE2809478A1; NL7802635A

Description

PATENT SPECIFICATION

I ( 21) Application No 9749/78 ( 22) Filed 13 March 1978 ( 31) Convention Application No 777 864 ( 32) Filed 15 March 1977 in ( 33) United States of America (US) < ( 44) Complete Specification published 19 Aug 1981 ( 51) INT CL 3 HO 1 J 61/02 ( 52) Index at acceptance Hi D 12 B 13 Y 12 B 1 12 B 47 Y 12 B 4 12 C 35 5 P 3 9 A 9 B 9 C 1 X 9 C 1 Y 9 CX 9 CY 9 H 9 Y ( 54) HIGH-INTENSITY DISCHARGE LAMPS ( 71) We, WESTINGHOUSE ELECTRIC CORPORATION of Westinghouse Building, Gateway Centre, Pittsburgh, Pennsylvania, United States of America, a company organised and existing under the laws of the Commonwealth of Pennsylvania, United States of America, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement:-

This invention has reference to high intensity discharge lamps.

United States Patent Specification No.

4032816 discloses an HID lamp which has a spring-loaded safety switch positioned between the outer protective envelope and the arc tube and electrically connected in series with one of the lamp electrodes.

When the lamp is operating normally, the safety switch is maintained in the closed position, but if the outer envelope is accidentally broken, the switch automatically opens to break the lamp energizing circuit and render the lamp inoperative.

United States Patent Specification No.

4013920 disclosed an HID lamp which has a resilient safety switch positioned proximate the inner surface of the dome portion of the protective outer envelope in contact with an extremity of a resilient leaf-spring portion of the arc tube frame, to maintain the switch in a closed position and which functions in the same manner as the switch of the aforesaid Rokosz application.

It has been reported that high-density discharge (HID) lamps, such as highpressure, mercury-vapor lamps, can constitute a safety hazard if the outer envelope is broken and the lamp continues to operate, because of the generation of short wavelength ultraviolet radiations, which are passed by the quartz arc tube.

Lamps which are protected by a fuse are generally known in the art and a projection lamp which is fused in order to prevent dangerous arcing currents is described in U.S Patent No 2,859,381.

High-intensity discharge lamps have also been provided with an incandescent filament included betweeen an arc tube and the outer envelope for purposes of ballasting the discharge and also generating some visible light While the purpose of ballasting the light-generating filament is not that of a link or safety switch, such a filament will normally oxidize and fail, particulary under lamp start-up conditions, if the outer envelope is broken since this prevents the filament to come in contact with air Of course, such a supplemental ballasting filament consumes an appreciable portion of the total power consumed by the lamp which decreases the lamp operating efficiency.

According to the present invention a high intensity discharge lamp comprises an elongate radiation-transmitting arc tube which is enclosed by and supported within a light-transmitting protective envelope which is opaque to short-wavelength ultraviolet radiations, said arc tube enclosing a discharge-sustaining filling and having electrodes positioned therein proximate the ends thereof, electrical leadin members sealed through said arc tube and connected to said electrodes, electrical adaptor means affixed to the outer surface of said protective envelope to facilitate electrical connection of said lamp to a source of electrical power, electrical conductor means electrically connecting said elctrical adaptor means to said electrical lead-in members, a thin strip-like conductor member affixed to and carried on a portion of the inner surface of said protective envelope which will normally fracture upon any breakage of said protective envelope, said thin strip-like conductor member being sufficiently fragile that it will break and ( 11) 1596 217 1,596,217 interrupt the electrical continuity thereof if the protective envelope portion upon which it is carried is fractured, and electrical contact means connecting said thin striplike conductor member in series with said electrical conductor means, whereby breakage of said protective envelope will fracture said thin strip-like conductor member and interrupt the electrical path between said electrical adaptor means and said electrical lead-in member to render said lamp inoperative.

In order that the invention can be more clearly understood, convenient is embodiments thereof will now be described, by way of example, with reference to the accompanying drawings in which:

Figure 1 is an elevational view showing a high-intensity discharge lamp with the thin strip-like conductor member extending peripherally within the dome portion of the protective envelope; Figure 2 is a fragmentary side elevational view of the lamp of Figure 1, showing further details of the electrical connections to the strip-like conductor; Figure 3 is a fragmentary plan view of Figure 2, showing the position of the thin strip-like conductor and further details of the elctrical conductor means; and Figure 4 is an elevational view of an alternative lamp wherein the thin strip-like conductor member extends longitudinally within protective envelope with electrical contact means connected thereto.

Referring to Figure 1, a high intensity discharge lamp 10 comprises an elongate radiation-transmitting quartz arc tube 12 which as shown in this embodiment has pressed-end portions 14, 14 a which is longitudinally disposed and supported within an elongated light transmitting protective envelope 16 The envelope as shown, has a neck portion 18 and a dome portion 20 The envelope 16 is formed of glass, such as borosilicate glass, which is transmissive for visible radiations and opaque with respect to the short-wavelength ultraviolet radiations which are generated within and transmitted through the arc tube 12 In accordance with conventional practices, the arc tube encloses a discharge sustaining filling 22 such as a small charge of mercury and a small charge of inert starting gas such as four torrs of argon The arc tube has electrodes 24, 24 a operatively positioned therein proximate the ends thereof and electrical lead-in members 26, 26 a sealed through the arc tube and connected to the electrodes A starting electrode 28 is positioned at one end of the arc tube and sealed through the pressed-end portion 14 a, and the starting electrode 28 is connected through a starting resistor 30 to the electrical conductor means 32.

Electrical adaptor means 34, such as a conventional screw-type base, is affixed to the outer surface of the protective envelope to facilitate electrical connection of the lamp 10 to a source of electrical power The electrical conductor means 32 connects the electrical adaptor means 34 to the electrical lead-in members 26, 26 a The electrical conductor means 32, as shown in this embodiment, includes an arc tube supporting frame 36 which comprises an elongated rigid metallic supporting member 38 longitudinally disposed within the protective envelope 16 and having extremity portions 40, 40 a proximate the dome portion 20 of the protective envelope 16.

Flexible ledf-spring metallic members 42, 42 a are affixed proximate the extremity portions 40, 40 a of the rigid metallic supporting member 38 laterally extended therefrom The end portions 44, 44 a of the leaf spring members 42, 42 a are urged toward the inner surface of the dome portion 20 of the protective envelope 16 by the resiliency of the leaf-spring members to provide a lateral and somewhat resilient support for the arc tube 12 The lamp and arc tube support as described hereinbefore are generally conventional.

In accordance with one embodiment of the present invention, and referring to Figures 1-3, there is provided a thin striplike conductor member 46 affixed to and carried on a portion of the inner surface of the protective envelope 16 which will normally fracture upon any breakage of the protective envelope The thin strip-like conductor member is sufficiently fragile that it wil break and interrupt the electrical continuity thereof if the protective envelope portion upon which it is carried is fractured.

The thin strip-like conductor member 46 may be made of any good conductive metal, such as silver A conductive silver stripe with a coating of screening paste on one side works well Electrical contact means connect the thin strip-like conductor member 46 in series with the electrical conductor means 32, whereby breakage of the protective envelope 16 will fracture the thin strip-like conductor member 46 and interrupt the electrical path between the electrical adaptor means 34 and the electrical lead-in members 26, 26 a to render the lamp 10 inoperative.

As shown in this embodiment the electrical contact means comprises an elongated connecting member 50 affixed at one end to one of the lead-in members 26 nearest the dome portion 20 of the protective envelope 16 As shown in this embodiment a supporting wire 52 preferably is embedded in the pressed-end portion 14 of the arc tube 12 proximate the dome portion of the protective envelope The 3 1,9,1 3 connecting member 50 is preferably affixed to the supporting wire 52 for additional strength The connecting member 50 generally extends laterally toward the inner surface of the dome portion 20 An elongated resilient spring 54 is affixed to one end of the connecting member 50 nearest the inner surface of the envelope 16 The resilient spring member 54 extends toward the inner surface of the dome portion 20 and is urged by its resiliency to contact the same The thin striplike conductor member 46, as shown in this embodiment, extends peripherally within the dome portion 20 of the protective envelope 16 The thin conductor member is positioned so as to contact the resilient spring member 54 and one of the leaf-spring members 40.

Electrical connection from the base 34 to the upper electrode 24 is thus through the frame 36, leaf spring 42, strip-like member 46, spring 54 and connecting member 50.

Thus, breakage of the envelope 16 breaks the thin strip-like member 46 and cuts off the power to the arc tube 12.

In accordance with another embodiment of the present invention, and referring to Figure 4, the thin strip-like conductor member extends longitudinally within the envelope 16 Electrical contact means, as shown in this embodiment, comprises resilient spring means comprising first, second and third spring members 58, 60 and 62 The first spring member 58 is affixed to the supporting frame 36 proximate the neck portion 18 of the protective envelope 16.

The first spring member 58 is forced by its resiliency into electrical contact with an end portion 56 of the strip-like conductor 46 a and the envelope inner surface The second resilient spring member 60 is affixed to the supporting frame 36 proximate the neck portion 18 of the protective envelope 16 and laterally extends toward the inner surface of the envelope and is forced by its resiliency into contact with the envelope inner surface at a point opposite the first resilient spring member 58 The third resilient spring member 62 is affixed to one of the lead-in members 26 and the supporting wire 52 proximate the dome portion 20 and laterally extends toward the inner surface of the envelope 16 and is forced by its resiliency into electrical contact with the other end portion 56 a of the strip-like conductor 46 a and the inner surface of the envelope The strip-like conductor 46 a as so arranged is electrically in circuit with the arc tube when the envelope is intact and the lamp is rendered inoperative upon breakage of the envelope 16.

Claims

WHAT WE CLAIM IS:-

1 A high-intensity discharge lamp which comprises an elongate radiationtransmitting arc tube which is enclosed by 65 and supported within a light-transmitting protective envelope which is opaque to short-wavelength ultraviolet radiations, said arc tube enclosing a discharge-sustaining filling and having electrodes positioned 70 therein proximate the ends thereof, electrical lead-in members sealed through said arc tube and connected to said electrodes, electrical adaptor means affixed to the outer surface of said protector 75 envelope to facilitate electrical connection of said lamp to a source of electrical power, electrical conductor means electrically connecting said electrical adaptor means to said electrical lead-in members, a thin strip 80 like conductor member affixed to and carried on a portion of the inner surface of said protective envelope which will normally fracture upon any breakage of said protective envelope, said thin strip-like 85 conductor member being sufficiently fragile that it will break and interrupt the electrical continuity thereof if the protective envelope portion upon which it is carried is fractured, and electrical contact means connecting 90 said thin strip-like conductor member in series with said electrical conductor means, whereby breakage of said protective envelope will fracture said thin strip-like conductor member and interrupt the 95 electrical path between said electrical adaptor means and said electrical lead-in members to render said lamp inoperative,

2 A high-intensity discharge; lamp comprising an elongate radiation 100 transmitting arc tube having pressed-end portions which is enclosed by and supported within a light-transmitting protective envelope having a neck portion and a dome portion and which is opaque to short 105 wavelength ultraviolet radiations, said arc tube enclosing a discharge-sustaining filling and paving electrodes positioned therein proximate the ends thereof, electrical leadin members sealed through said arc tube 110 and connected to said electrodes, electrical adaptor means affixed to the outer surface of said protective envelope to facilitate electrical connection of said lamp to a source of electrical power, and electrical 115 conductor means electrically connecting said electrical adaptor means to said electrical lead-in members, said electrical conductor means including an arc tube supporting frame comprising an elongated rigid 120 metallic supporting member longitudinally disposed within -said protective envelope and having extremity portions proximate said dome portion of said protective envelope, flexible leaf-spring metallic supporting mem 125 bers affixed proximate the extremity portions of said rigid metallic supporting member and laterally extending therefrom with the end 1,596,217 4 1,596,217 4 portions of said leaf-spring members urged toward the inner surface of said dome portion of said protective envelope by the resiliency of said leaf-spring members to provide a lateral and somewhat resilient support for said arc tube, a thin strip-like conductor member affixed to and carried on a portion of the inner surface of said protective envelope which will normally fracture upon any breakage of said protective envelope, said thin strip-like conductor member being sufficiently fragile that it will break and interrupt the electrical continuity thereof if the protective envelope portion upon which it is carried is fractured and electrical contact means connecting said thin striplike conductor member in series with said electrical conductor means, whereby breakage of said protective envelope will fracture said thin strip-like conductor member and interrupt the electrical path between said elctrical adaptor means and said electrical lead-in members to render said lamp inoperative.

3 A lamp according to claim 2, wherein the electrical contact means comprises an elongate connecting member affixed at one end to one of the lead-in members nearest the dome portion of the protective envelope, said connecting member generally extending laterally toward the inner surface of said dome portion, and elongate resilient spring member affixed to one end of said connecting member nearest said inner surface of said envelope, said resilient spring member extending toward said inner surface of said dome portion and urged by its resiliency to contact same.

4 A lamp according to claim 3, wherein the thin strip-like conductor member extends peripherally within said dome portion of the protective envelope, said thin conductor member being positioned so as to contact the resilient spring member and one of the leaf-spring members, whereby breakage of said envelope breaks said thin strip-like member and cuts off the power to the arc tube.

A lamp according to claim 2, wherein the thin strip-like conductor member extends longitudinally within the envelope.

6 A lamp according to claim 5, wherein the electrical contact means comprises resilient spring means comprising a first spring member affixed to the supporting frame proximate the neck portion of the protective envelope and forced by its resiliency into electrical contact with an end portion of the strip-like conductor and the envelope inner surface, a second resilient spring member affixed to said supporting frame proximate said neck portion of said protective envelope and laterally extending towards the inner surface of said envelope and forced by its resiliency into contact with said envelope inner surface at a point opposite said first resilient spring member, a third resilient spring member affixed to one of said lead-in members proximate said dome portion and laterally extending towards said inner surface of said envelope and forced by its resiliency into electrical contact with the other end portion of said strip-like conductor and the inner surface of said envelope, whereby said thin strip-like conductor is electrically conductive when said envelope is unbroken and electrically non-conductive upon breakage of said envelope.

7 A lamp according to any of claims 2 to 6, wherein a supporting wire is embedded in the pressed-end portion of said arc tube proximate said dome portion of the protective envelope.

8 A lamp according to claim 7 when dependent on claim 3, wherein the elongated connecting member is also affixed to the supporting wire.

9 A lamp according to claim 7 when dependent on claim 6, wherein the third resilient spring member is also affixed to the supporting wire.

High intensity discharge lamps as claimed in claim 1 or 2 and substantially as described herein with particular reference to Figures 1 to 3 or Figure 4 of the accompanying drawings.

RONALD VAN BERLYN Printed for Her Majesty's Stationery Office by the Courier Press, Leamington Spa, 1981.

Published by the Patent Office, 25 Southampton Buildings, London, WC 2 A l AY, from which copies may be obtained.

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